This invention relates to latching micro magnetic relays.
More particularly, the present invention relates to latching micro magnetic relays, various applications, and methods of manufacture.
High frequency switchable band pass filters are widely used in telecom and datacom applications. Competition and new applications have driven the filters used in this field to smaller size, better performance, higher frequency, and yet at very low cost. Gallium arsenide (GaAs) field effect transistor (FET) based switching filters have been developed for this purpose. The GaAs FET based switching filters are inexpensive but they do not perform at frequencies above 2 GHz.
Recently, novel latching micro magnetic relays were discovered. The novel latching micro magnetic relay is based on preferential magnetization of a soft magnetic cantilever in a permanent external magnetic field. Switching between two magnetic states is accomplished by momentarily changing the direction of the cantilever""s magnetization by passing a short current pulse through a planar coil situated adjacent the cantilever. Once the relay is switched, it is held in this nonvolatile state (latched) by the permanent external magnetic field. Additional information as to the construction and operation of the novel latching micro magnetic relay is disclosed in a co-pending United States patent application entitled xe2x80x9cElectronically Switching Latching Micro-Magnetic Relay and Method of Operating Samexe2x80x9d, with Ser. No. 09/496,446, filing date Feb. 2, 2000, and incorporated herein by reference.
Latching micro magnetic relays have never been used as switching apparatus in, for example, high frequency switchable band pass filters.
Accordingly, it is an object the present invention to provide new and improved micro magnetic switching apparatus for use in, for example, high frequency switchable band pass filters and the like.
Another object of the present invention is to provide new and improved micro magnetic switching apparatus in a high frequency switchable band pass filter with very low insertion loss and high Q at very high frequency, e.g., up to 20 GHz.
And another object of the present invention is to provide new and improved micro magnetic switching apparatus used in a high frequency switchable band pass filter that is smaller size, has better performance, is inexpensive, and operates at much higher frequency.
A further object of the present invention is to provide new and improved micro magnetic switching apparatus constructed to require substantially smaller switching currents to perform the switching function.
A further object of the present invention is to provide new and improved micro magnetic switching apparatus for use in electronic circuits, such as duplexers, 1xc3x972 multiplexing switches, 2xc3x972 differential switches, and the like.
Briefly, to achieve the desired objects of the present invention in accordance with a preferred embodiment thereof, provided is micro magnetic switching apparatus including latching micro magnetic relays. A permanent magnet is supported on a base. A coil is supported by the base and positioned to define a plurality of sides. A plurality of latching micro magnetic relays each includes a magnetic cantilever positioned to open an electric circuit in a first orientation and to close the electric circuit in a second orientation. One each of the latching micro magnetic relays is mounted adjacent each of the plurality of sides of the coil and adjacent the permanent magnet so as to be latched in one of the first and second orientations when the coil is not activated. When the coil is activated the latching micro magnetic relays switch to the other of the first and second orientations and are latched in the other of the first and second orientations by the permanent magnet. Because of the latching feature, the micro magnetic switching apparatus uses zero latching current once the switching has been accomplished. The plurality of latching micro magnetic relays can each open and close a different electric circuit or they can all operate on a common electric circuit.
In some embodiments, the micro magnetic switching apparatus includes a plurality of coils with each coil defining a plurality of sides and each side associated with a latching micro magnetic relay. These embodiments may be fabricated on a single base with a single permanent magnet or they could be fabricated as individual devices, each on a base with a permanent magnet. Also, while the permanent magnet (e.g., a piece of magnetized magnetic material) is believed to be the most efficient and easy to fabricate, it will be understood that in some specific applications it may be desirable to form the permanent magnet from material that is magnetized by a small electric current that is applied when the circuit is in operation.
In a further embodiment, micro magnetic switching apparatus is constructed with a base and a permanent magnet supported by the base. A coil is supported by the base and folded to define a first portion and a second portion with the first portion providing a first magnetic field and the second portion providing a second magnetic field when the coil is activated. The first and second portions are positioned so that the first magnetic field and the second magnetic field combine to produce a composite magnetic field greater than either of the first and second magnetic fields between the first and second portions. A latching micro magnetic relay, including a magnetic cantilever, is positioned between the first and second portions of the coil. The latching micro magnetic relay is constructed to open an electric circuit in a first orientation and to close the electric circuit in a second orientation and is further positioned relative to the permanent magnet so as to be latched in one of the first and second orientations when the coil is not activated and to switch to the other of the first and second orientations when the coil is activated and to be latched in the other of the first and second orientations by the permanent magnet. Thus, this novel embodiment uses substantially less switching current, because of the folded coil.